Patchwork [RFC] powerpc: restore TOC when static longjmp to shared object

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Submitter Adhemerval Zanella Netto
Date May 16, 2018, 8:55 p.m.
Message ID <1e218f7a-955b-fb16-70fb-4637d31a9ccb@linaro.org>
Download mbox | patch
Permalink /patch/27307/
State New
Headers show

Comments

Adhemerval Zanella Netto - May 16, 2018, 8:55 p.m.
On 16/05/2018 16:36, Rogerio Alves wrote:
> Attached to this email I am sending the first version of the patch but I have a problem with this patch. I can't make the test work. By some reason it can't find the .so needed by the test:
> 
> FAIL:
> ./setjmp-bug21895.so: cannot open shared object file: No such file or directory
> 
> Notice that if I manually execute the command on make check stdout inside the folder it works fine. I'd appreciate any help on that.
> 
> Regards
> 
> Em 15-05-2018 17:48, Tulio Magno Quites Machado Filho escreveu:
>> Florian Weimer <fw@deneb.enyo.de> writes:
>>
>>> * Rogerio Alves:
>>>
>>>> One simple solution would be always restore the TOC pointer by uncomment
>>>> the line bellow:
>>>>
>>>> /*     std r2,FRAME_TOC_SAVE(r1)       Restore the TOC save area.  */
>>>>
>>>> Or maybe we can check if we have a valid TOC pointer before restore it,
>>>> instead #if defined SHARED.
>>>
>>> Is the register reserved for the TOC pointer in static builds, too?
>>> Then I suggest to unconditionally save nad restore it; not doing so
>>> looks like a pointless micro-optimization.
>>>
>>> Another problem with sharing jump buffers across static dlopen is that
>>> you might not have identical pointer guard values.
>>>
>>>> I would like to request for comments on this matter: Should we fix/work
>>>> this? Is feasible to change longjmp to always restore TOC pointer?
>>>
>>> Does setjmp already save it unonditionally?
>>>
>>> Removal of static dlopen is still some time away; it's likely not
>>> going to happen in this cycle, and the fix looks simple enough.
>>
>> If static dlopen is still going to be supported for some cycles, I also agree
>> it should be saved and restored unconditionally.
>>
> 
> 0001-PATCH-v1-powerpc-Always-restore-TOC-on-longjmp.patch
> 
> 
> From eb9895f1548c8f6e1826095aee3221eaf9ce84c9 Mon Sep 17 00:00:00 2001
> From: Rogerio Alves <rcardoso@linux.vnet.ibm.com>
> Date: Wed, 16 May 2018 14:20:53 -0500
> Subject: [PATCH] [PATCH v1] powerpc: Always restore TOC on longjmp.
> 
> This patch change longjmp to always restore the TOC pointer (r2 register)
> to the caller frame on powerpc. This is related to bug 21895[1] that reports
> a situation where you have a static longjmp to a shared object file.
> 
> [1] https://sourceware.org/bugzilla/show_bug.cgi?id=21895

Please indicate where you actually tested this patch (since the make check
is broken).

> 
> 2018-05-16 Rogerio A. Cardoso <rcardoso@linux.vnet.ibm.com>
> 
> 	*sysdeps/powerpc/powerpc64/__longjmp-common.S: Remove condition code for
> 	restore r2 on longjmp.
> 	*setjmp/Makefile: Include test build directives.

You need to add each rules you might add, the ones you are changing, and
removing (check other ChangeLog for example).

> 	*setjmp/setjmp-bug21895.c: new test file.
> 	*setjmp/tst-setjmp-bug21895.c: new test file.

Capitalize the new.

> ---
>  setjmp/Makefile                              | 18 ++++++--
>  setjmp/setjmp-bug21895.c                     | 42 ++++++++++++++++++
>  setjmp/tst-setjmp-bug21895.c                 | 65 ++++++++++++++++++++++++++++
>  sysdeps/powerpc/powerpc64/__longjmp-common.S |  5 +--
>  4 files changed, 123 insertions(+), 7 deletions(-)
>  create mode 100644 setjmp/setjmp-bug21895.c
>  create mode 100644 setjmp/tst-setjmp-bug21895.c
> 
> diff --git a/setjmp/Makefile b/setjmp/Makefile
> index dc2fcc6..e715ee6 100644
> --- a/setjmp/Makefile
> +++ b/setjmp/Makefile
> @@ -22,16 +22,28 @@ subdir	:= setjmp
>  
>  include ../Makeconfig
>  
> -headers	:= setjmp.h bits/setjmp.h bits/setjmp2.h
> +headers	:= setjmp.h bits/setjmp.h bits/setjmp2.h bits/dlfcn.h dlfcn/dlfcn.h

Why does it require adding more headers here? This is meant be installed afaik
and I am not following the requirement here.

>  
>  routines	:= setjmp sigjmp bsd-setjmp bsd-_setjmp \
>  		   longjmp __longjmp jmp-unwind
>  
>  tests		:= tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \
> -		   tst-sigsetjmp tst-setjmp-static
> +		   tst-sigsetjmp tst-setjmp-static tst-setjmp-bug21895
> +

Since the idea is test for static build I would recommend to follow the other
static naming, i.e, tst-setjmp-bug21895-static.

>  tests-static	:= tst-setjmp-static
>  
> +modules-names = setjmp-bug21895
>  
>  include ../Rules
>  
> -$(objpfx)tst-setjmp-fp: $(libm)

I do not think you meant to remove this rule.

> +test-modules = $(addprefix $(objpfx),$(addsuffix .so,$(modules-names)))
> +
> +ifeq ($(build-shared),yes)
> +tests: $(test-modules)
> +endif
> +
> +$(objpfx)setjmp-bug21895.so: $(libdl)
> +$(objpfx)tst-setjmp-bug21895: $(libdl)
> +$(objpfx)tst-setjmp-bug21895.out: $(objpfx)setjmp-bug21895.so
> +
> +$(objpfx)ts-tsetjmp-fp: $(libm)

I think the idea is to build the test even if build-shared is set to no (since
you are testing static linking).  I think what you want is:

---


---

At least with qemu-static it seems to work with your patch.


> diff --git a/setjmp/setjmp-bug21895.c b/setjmp/setjmp-bug21895.c
> new file mode 100644
> index 0000000..d6f5516
> --- /dev/null
> +++ b/setjmp/setjmp-bug21895.c
> @@ -0,0 +1,42 @@
> +/* Copyright (C) 2013-2018 Free Software Foundation, Inc.

Wrong Copyright date span and missing one line description.

> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Test that setjmp/longjmp interoperability with static dlopen.
> +   Bugzila #21895.  */
> +#include <alloca.h>
> +#include <string.h>
> +#include <setjmp.h>
> +
> +jmp_buf jb;
> +void (*bar)(jmp_buf);
> +
> +void
> +lbar (int i, ...)
> +{
> +  bar(jb);
> +  for(;;);
> +}
> +
> +void
> +foo (void)
> +{
> +  int i = setjmp(jb);
> +  char *c = alloca(256);
> +  memset(c, 0, 256);
> +  lbar(i);
> +  for(;;);
> +}
> diff --git a/setjmp/tst-setjmp-bug21895.c b/setjmp/tst-setjmp-bug21895.c
> new file mode 100644
> index 0000000..5333494
> --- /dev/null
> +++ b/setjmp/tst-setjmp-bug21895.c
> @@ -0,0 +1,65 @@
> +/* Copyright (C) 2013-2018 Free Software Foundation, Inc.

Wrong Copyright date span and missing one line description.

> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Test that setjmp/longjmp interoperability with static dlopen.
> +   Bugzila #21895.  */
> +
> +#include <setjmp.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <dlfcn.h>
> +
> +static void
> +bar (jmp_buf jb)
> +{
> +  static int i;
> +  if (i++==1) exit(0);
> +  longjmp(jb, i);
> +}
> +
> +static int
> +do_test (void)
> +{
> +  void *h = dlopen("./setjmp-bug21895.so", RTLD_NOW);

Better to just use name, since on test environment variable in Makefile
change I proposed the path to build setjmp folder is already on the
LD_LIBRARY_PATH list.

> +  if (!h) {
> +    puts ("FAIL: ");
> +    puts (dlerror());
> +    return 1;
> +  }

Wrong indentation and please use libsupport macros. 

> +
> +  void (*pfoo)(void) = dlsym(h, "foo");
> +  if (!pfoo) {
> +    puts ("FAIL: ");
> +    puts (dlerror());
> +    return 1;
> +  }
> +
> +  void (**ppbar)(jmp_buf) = dlsym(h, "bar");
> +  if (!ppbar) {
> +    puts ("FAIL: ");
> +    puts (dlerror());
> +    return 1;
> +  }
> +
> +  *ppbar = bar;
> +  pfoo();
> +
> +  for(;;);
> +}
> +
> +#define TEST_FUNCTION do_test ()
> +#include "../test-skeleton.c"

We do not use test-skeleton.c inclusion any longer, use libsupport 
(support/test-driver.c).

> diff --git a/sysdeps/powerpc/powerpc64/__longjmp-common.S b/sysdeps/powerpc/powerpc64/__longjmp-common.S
> index 0e10b8d..a5973c9 100644
> --- a/sysdeps/powerpc/powerpc64/__longjmp-common.S
> +++ b/sysdeps/powerpc/powerpc64/__longjmp-common.S
> @@ -130,9 +130,6 @@ L(no_vmx):
>  	ld r0,(JB_LR*8)(r3)
>  	ld r14,((JB_GPRS+0)*8)(r3)
>  	lfd fp14,((JB_FPRS+0)*8)(r3)
> -#if defined SHARED && !IS_IN (rtld)
> -	std r2,FRAME_TOC_SAVE(r1)	/* Restore the callers TOC save area.  */
> -#endif
>  	ld r15,((JB_GPRS+1)*8)(r3)
>  	lfd fp15,((JB_FPRS+1)*8)(r3)
>  	ld r16,((JB_GPRS+2)*8)(r3)
> @@ -152,7 +149,7 @@ L(no_vmx):
>  	second argument (-4@4), and target address (8@0), respectively.  */
>  	LIBC_PROBE (longjmp, 3, 8@3, -4@4, 8@0)
>  	mtlr r0
> -/* 	std r2,FRAME_TOC_SAVE(r1)	Restore the TOC save area.  */
> + 	std r2,FRAME_TOC_SAVE(r1)	/* Restore the TOC save area.  */

Space before tab in indent.

>  	ld r21,((JB_GPRS+7)*8)(r3)
>  	lfd fp21,((JB_FPRS+7)*8)(r3)
>  	ld r22,((JB_GPRS+8)*8)(r3)
> -- 2.7.4
>

Patch

diff --git a/setjmp/Makefile b/setjmp/Makefile
index dc2fcc6..231474b 100644
--- a/setjmp/Makefile
+++ b/setjmp/Makefile
@@ -28,10 +28,17 @@  routines    := setjmp sigjmp bsd-setjmp bsd-_setjmp \
                   longjmp __longjmp jmp-unwind
 
 tests          := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \
-                  tst-sigsetjmp tst-setjmp-static
-tests-static   := tst-setjmp-static
+                  tst-sigsetjmp tst-setjmp-static tst-setjmp-bug21895-static
 
+tests-static   := tst-setjmp-static tst-setjmp-bug21895-static
+
+modules-names = setjmp-bug21895
 
 include ../Rules
 
 $(objpfx)tst-setjmp-fp: $(libm)
+$(objpfx)tst-setjmp-bug21895-static: $(common-objpfx)dlfcn/libdl.a
+$(objpfx)tst-setjmp-bug21895-static.out: $(objpfx)setjmp-bug21895.so
+
+tst-setjmp-bug21895-static-ENV = \
+  LD_LIBRARY_PATH=$(objpfx):$(common-objpfx):$(common-objpfx)setjmp:$(common-objpfx)elf